The invention relates to electrical circuit arrangements and more particularly to temperature-responsive electrical circuit arrangements. One such circuit arrangement to be described by way of example is for use with a temperature detector of the type whose capability of accepting an electrical charge increases with temperature; the circuit arrangement determines the electrical state of the detector and thus can determine whether its temperature is excessive. Such a temperature detector may advantageously be of linear form so as to be mountable around an area whose temperature is to be monitored.